ABSTRACT
Zinc deficiency was recognized as a practical problem in domestic animals in the early 1950s. Radioactive tracers are identical in all respects to normal matter, except for one property: isotopic tracer atoms have a tag or label that makes them instantly recognizable among a population of normal atoms. Radioactivity is released as the nucleus becomes transformed to a stable configuration. The random nature of decay and the rapidity of disintegration determines the usefulness of an isotope for biological work. The practical significance of zinc was not realized until peanut meal was used as the protein source for swine diets and showed that supplemental zinc was required to prevent or cure parakeratosis. The absorption/reabsorption of the combined dietary and endogenous pancreatic pools of zinc is essential for the maintenance of zinc homeostasis. Zinc deficiency produced by use of a nonphytate containing protein source provides a model suitable as an academic curiosity for the study of zinc metabolism.
